Apparatus for controlling fluid volume in fluid couplings



June 12, 1945. M. H. BLANK 2,377,851

APPARATUS FOR CONTROLLING FLUID VOLUME IN FLUID COUPLINGS Filed Feb. 17,1941 4 $h96ts Sh99t 1 lNveNToR MERTON H. Bumu MM lino auevs June 12,1945'. BLANK 2,377,851

S APPARATUS FOR CONTROLLING FLUID VOLUME IN FLUID COUPLINGS Filed Feb.17. 1941 4 Sheets-Sheet 2 lmmton.

Memo H. BLINK 0p 2 0 Arroaaevs June 12, 1945. M. H, BLANK APPARATUS FORCONTROLLING FLUID VOLUME IN FLUID COUPLINGS Filed Feb. 17. 1941 4Sheets-Sheet 3 Iuvcuroa MERTON H. BLHNK B W M. H. BLANK 2,377,851

APPARATUS FOR CONTROLLING FLUID VOLUME IN FLUID COUPLINGS June 12, 1945.

Filed Feb. 17, 1941 4 Sheets-Sheet 4 Jrwm MERTON n. BLANK,

.used as the active Patented June 12, 1945 APPARATUS FOR VOLUME MertonH. Blank, Pleasant Ridge,

CONTROLLING 1N FLUID COUPLINGS FLUID Mich assiznor American Blower Conn,Detroit, Mich a corporation 01' Delaware Application February 17, 1941,Serial No. 379,828

9 Claims.

encountered in accurately variation of small variable This trouble isencoun- Difliculty has been regulating the speed speed fluid couplings.

chamber widely alters the speed change between the runner and theimpeller. To produce sufficiently small increments of change of speeddifated thereby toicontrolling fluid flow to the ham not suflicientlysensitive to fluid coupling will be regulated in relatively smallincrements of speed It is an object of the object 01' the invention toprovide her i 'or receiving work fluid, which chamber is divided bymeans or the two compartments in from the impelller to the runner.

It is another object 01' the invention to provide a fluid drive inaccordance with the foregoing obiect wherein the fluid volume change inthe work chamber afl'ects the body or fluid in both a fluid coupling.

It is another object of the invention to control the admission of workfluid to the work chamber or a fluid coupling by means of a fixedorifice.

is another object of the invention to provide a fluid coupling inaccordance with the foreoing object or fluid admitted to the workchamber.

It is another object oi the invention to provide a control apparatus forregulating the pressure of the working fluid which is applied through afixed orifice associated with the work chamber of the coupling.

for more emcient cooling oil circulated.

It is another object of the invention to provide a variable speed fluidcoupling wherein a relatively large quantity of fluid can be admitted tothe work chamber without greatly aflecting the speed diiierential.

A further object of the resistance to regulate the fluid flowtherethrough.

Further objects apparent from the description and In the drawings:

Figure l is a plan view, partially in cross-section, or a fluid couplingdrive mechanism showing the power input and take-oi! from the coupling.

Fi ure 2 along line and advantages will become is a verticalcross-sectional view taken 2-4 of Figure 1.

Figure 3 is an elevatlonal view of a portion of the runner ot the fluidcoupling and is taken along line 3-3 of Figure 2;

an elevatlonal view or a portion of the runner or the fluid coupling andis taken along the line Figure 5 is a. fluid coupling as applied fordriving the supercharger. control system for regulating fllfld flow tothe coupling.

Figure 6 is a view the volume control to the coupling.

Figure '1 is a view imilar to Figure 5 but shows the ure control offluid circulating to the fluid coupling for regulatingthe fluid flow toa conventional type of couplin In this invention the fluid coupling isdisclosed as applied for use upon an aircraft for driving The speed ofchange must be in order to provide complete' regulation or thecarburation or the aircraft engine. It can readily be appreciated thatwhile the application the fluid coupling to the supercharger or theaircraft is a articular application, yet the e is such that it merelyshows one applied form of the invention. It is within the conce 'tion orthis invention to accurately control the speed or any driven apparatuswhich is connected to a power source through a fluid coupling. Theneed'for an accurate control of the speed or a driven mechanism. whendriven by a fluid couplin is accentuated when the nine 01 the 00 mm i8reduced and even more so when the couplings are operated at relativelyhigh speeds. The application or the disclosed in this invention, ofapplication wherein extremely acute, and which requires extreme accuracyover the output speed or the runner of the fluid coupling.

This invention consists or a housin "I which is provided ior. enclosinthe operating mechanism oi the fluid coupling. As disclosed in thisapplication, the housin III is an independent member. However, thishousing could be proan integral part of the apparatus upon fluidcoupling is to be mounted. The

means, wherein the fluid discha ged through the leak ports or iscollected, and is connected with an oil reservoir which is Figure butshows the fluid flow similar to for regulating accurately by suitableeither a separate case of aircraft, the case of the engin The fluid collkeyed upon a shaft oil reser oir can be the crank consists of animpeller ll it which is bearinfled in the housing III by means oi thebearing sleeves I3 and Il. The impeller H has an arcuately shaped innerface contour ii and is provided with a plurality of radially disposedvanes 16, which structure is conventional for fluid couplings. The

the drawings.

the arcuate ace u o! the runner slots 25 have their outer ends near thearcuate face i A 38 are provide an interrupted slots l8 interrupt thethe impeller.

The impeller II is means of the key member 29 and has a boss ll whichengages a gear 3| also' keyed to the snart llbymeansoiakey 32. Athrusrin ilisin threaded engagement with the shaft l2 and bears against theup-t flange 34 oi the bearing I! to absorb the thrust of the endwlsethrust of the impeller II.

A cylindrical chamber 31 is provided with an open end whlchis inengagement with an annular flanged recess 38 provided on.the impellerll. Bolts 38 extend through the annular flange. or the recess 33 intothreaded engagement with the cylindrical chamber 31 the chamber to theimpeller ll. extends rearwardly of the impeller an inwardly directedwall M which carries a boss 42. The boss 12 is bearinged upon the shaltsleeve 26 by meanso! the'bearing bushin 43. The cylindrical chamber 31thus encloses the runner is, and the arcuately curved wall 22 oi therunner is divides the chamber formed by the impeller II and thecylindrical chamber 31 into two compartments.

ent provided between the im- IB the fluid retained is adapted toactively circulate between it upon rotation is is driven keyed in theshalt l2 by oi the surface of the fluid from the center or by means ofthe collar 81 which is in threaded the chamber 31 is the same in both01' the comengagement with the sleeve shaft 26. The gear will advance orrecede from the center of rota- ID. The sleeve shaft 69 extends throughthe wall the runner is is bearinged in the sleeve bearings and isretained thereon by means of the collar bosses l6 and 41 respectivelywhich are an inportion 01' the shaft 69. An oil seal 19 is protegraipart of the housing ill. The sleeve bearing vided around the end portioniii of the sleeve has a flange 48 which engages the boss 41 for shaft69.

longitudinal location of the ring 28, while the 20 The step-up gearratio between the gears 55 and 3| dri es the fluid coupling at a higherspeed with the boss 46. for longitudinal positioning'of than is obtainedby the power source so that a wall closure member 50 which has anextendm y e any desired gear ratio according to the ing annular portion5i which surrounds and ened required of the driven apparatus. Thiscloses the end of the shaft 12. Gear ratio can either increase the speedtaken The interior of the shaft l2 hasalongitudinally from the runner fthe fluid coupling, or the ext bore 52 which communicates with a speedcan be reduced in accordance with the depassageway 53 provided in theend closure plate sired requirements- 50. The passageway 53 communicateswith the The bearing sleeves 53 and 72 are 0011- pres ure side of an onpump so that the interior nected to a Source of pressure which lubriofthe shaft 52 s under pressure and is filled cates the bearings. Each ofthe bearings l3, H, with oil when the fluid coupling is functioning. 53and 12 is provided i a p ng co nection ing portion BI 01' the closureplate 60 for preventconnected by means of the d it 8 to a suitm leakageof n t t housing 1 from the 40 able source oi oil pressure, such as theoil pump pre'ssm-e source from within th shaft 51 on the aircraftengine. A plurality of oil holes The gear 3|, secured upon the shaft l2,en- 3218 p ided in the wall of the shaft It to lubrigages a gear 55which is keyed upon a shaft 56, e the bearings 20 and 2i, an also t aidThe shaft 55 has an enlarged portio 51 which' the oil holes 83. Thebearing 43 is provided with with a fastening plate 59 on the end thereofwhich me of wet and, as disclosed m this mVen the oil within the chamber45 is varied To cona the 53 of power is the engine of the mp trol thevolume of 011 within the chamber 45 fluid craft. 1:; is well understoodhowever that this 55 inlet ports 86 connect the in e io or the shaft thecon 1m 1s ut as to the particular source One or more leak ports 81 isprovided around the of power wgich 11 be connected to t fastenperipheryof the cylindrical chamber 11. The in late 59.

fif gear 55 is secured upon the shaft 5 by continuously bleed a portionof the oil from the means of the collar 6! which is in threaded en-Working Chamber Of e fluid up ing. he oil gagement with the shaft 56 andretaining-the gear is continuously supplled the Working chamber betweenthe collar GI and the enlarged portion 85 i the fluid coupling by meansof the ports 86 56 to prevent oil from leaking from the housing Videdfor'contlfimng the Velume- 9f il Passin g through the ports 86 forregulating the speed The output from the fluid couplin is transoutput ofthe runner I9. While the applicant mitted through a gear keyed upon thesleeve is l a p ifi means for accomplishing hi shaft 26 by m a 01 th key88, Th gear is function which will be hereinafter described, yet isretained in position upon the shaft sleeve 28 7 for the purpose ofunderstanding the function or chamber sense that the increment of speedchange fluid between which entire the impeller body of fluid is activeior power transmission between the impeller and the runner. In thisinvention, however, the applicant has provided an enlarged work chamberin which the body of fluid is divided into an active work fluid iortransmitting power between the impeller and the runner, and an inactivebody which is retained within that portion of the chamber which isoutside the confines of the impeller and her chamber. The radial slotsII and in the body of the runner provide constant communication betweenthe work fluid within the compartment 5 provided between the runner l9and the work fluid in the compartment It so that when fluid is admittedto or taken from the interior of the cylindrical casing 31 the entirevolume of fluid is affected, but only that percentage oi the totalvolume removed from or added to the chamber 65 is effective for causingvariation in the speed ratio between -the impeller and the runner sinceit is only the body 01' fluid in the chamber l5 which is actively trans-When fluid coupling is rotated by the power source the liquid within thecoupling will collect in a ring around the periphery of the chamber and,for purposes of description, the ring can be the dotted line "A."

31 fills the volume indicated by the line A, which volume is bet of thecylindrical chamber ratio will be obtained between and the runner 19, Inorder to increase the speed of the runner is with respect the impeller Ha greater quantity of oil is required to be added to the working chamber45. The control means for regulating the quantity of oil flowing throughthe ports 86 is operated to increase the flow through the ports 88whereby the oil volume indicated by the line B. It can be readily seenirom the oil volumes indicated by the lines that the total volume of oilhandled is considthat which would normally to raise the volume of oilwithin the 7 volume A to the volume B, whereby the extreme sensitivityof the fluid coupling to changes in volume is reduced so that likevolumes of oil as previously handled will, when handled in theappiicant's apparatus, produce less speed change between the runner isand the impeller ii since the total volume of oil effective tor powertransmission within the compartment 45 will be less. thus seen that theapplicant has reduced the sensitivity oi. the fluid coupling with regardto changes in the volume of oil passing through the coupling, and has atthe same time incre the sensitivity in the of the runner with respectthe impeller is considerably reduced over thatwhich would normally occurupon handlin the same quantity of oil in the conventional WW8 oiapparatus.

as heretofore described, is

The a paratus,

upon aircrait for driving the adaptable for use supercharger, which mustbe re a relatively small increments 01 speed increase for smallincrements of altitude and the device must be fully and completelyresponsive to any sud the aircraft.

The engine 0! of the aircraft is connected to the gear 55 of thehydraulic coupling heretofore described so that the gear Ii in turn isdriven from the engine all and thereby peller ii. The runner it drivesthe supercharger si through means of the gears ti and Cl heretotorereferred The housing Ni is provided with a drain opening 92 to permit agravity return of oil from the housing It to the crank case of theengine lilthrough a conduit at. This oil return can either be by gravityor by a pressure return as desired.

As heretofore mentioned the applicant provides a positive pressurewithin the the shaft It to teed fluid through the portsor and controlsthis pressure to regulate the quantity oi oil passed through theorifices it. This trol mechanism consists of a fluid pump Bl connectedby a conduit 95 to a suitable source or oil crank case or t enconnectsthe fluid pump with the inlet opening 53 of the shaft i! to conductfluid under pressure from the pump 54 to the interior oi the shalt ii.

A by-pass pressure reliei valve 91 is provided in a conduit stconnecting the discharge side of the pump M and the housing N. Thispressure relief valve 01 is provided withan adjustable control spring 89for regulating the pressure at which the valve will open to permit oilor liquid to be circulated through the conduit 8% for return to thehousing is or to the crank case of the engine.

A control a conduit III which interconnects the discharge side 01 thepump it with the parallels the conduit 90 so that the pressure reliefvalve 91 and the control valve Hill are arranged in parallel controlvalve lilfl rise oi the aircraft,

which is responsive to an apparatus to be controlled. As applied toaircraft, the valve lilil will be operated in response to a control "I:upon a rise and fall oi the The applicant is not limited to the specifictype of control disclosed in this application since this control ismerelyrepresentative or a system in which applicant's invention isuseiul.

The pressure relief valve 51 is set to open at a predetermined maximumpressure, according to the compression of the spring 88, which spring isadjustable. This pressure relief valve thus prevents overloading thesystem regardless of the volume of oil delivered by the pump 9| and ineffect becomes a constant pressure valve for the conduit 96 when thevalve "I0 is completely closed. This condition exists only when theaircraft is at extreme altitude.

The valve I" is a variable orifice or choke valve ior throttling theflow of oil lay-passed therethrough to the housing lb or to the crankcase of the engine. Under normalvoperating conditions the valve I00determines the pressure existing in the conduits NH and N, which valvein tum it operated in pow t0 the barometric control I02 so that thepressure in the conduit 96 is aflected, or increased as the barometriccontrol tends to close the valve I00.

'Under normal operation, when the aircraft is on the ground or at lowaltitude, the valve l0.

will be completely open at which time the pressure in the conduit ismaintained at a minimum pressure by means of a pressure relief valveI03, the minimum pressure relief valve being provided to maintainsufllcient pressure within the shaft II to insure lubrication of thebearings within the fluid coupling. At this time the pressure reliei'valve 91 is closed, and the valve I00 is capable of passing the fullvolume or oil discharged from the pump 04 regardless of the speed of theengine as long as the valve I00 is in wide open position. At lowaltitude the use of the supercharger is not required so that at thistime the runner I9 will not be functioning except for the speeddeveloped by the maximum slip allowed in the fluid coupling.

When the pressure control valve I00 tends to throttle the flow of fluiddischarged from the pump 90 through the by-pass conduit l0l, pressurebuilds up in the line 98. Throttling of the valve 100 can either -byaccomplished by the barometric control I02 or by other satisfactorycontrol devices.

When the pressure increases in the conduit 90 the volume of oil passedby the fixed restrictions 88 is increased, the volume of oil passed bythe restrictions 06 being as of the square root of the pressuredifierence across the restriction. Since the increased flow through therestri tions 06 is relatively small for a relatively large ncrease inpressure in the conduit 98 it can readily be appreciated that the volumeof fluid or oil added to the working chamber of the fluid coupling isreadily controllable and is controllable to theextent of handling moreminute quantities of oil for a given change of the control mechanism.The pressure difference across the orifices 80 is always a predeterminedand constant factor and the flow therethrough increases at apredetermined rate in accordance with the increase of pressure on theinlet side of the orifice. This rate of increase of how through theorifices 08 can be calibrated as against the discharge of fluid from thecylindrical chamber 31 through the leak ports 81, so that when thecontrol valve I00 is closed and the maximum pressure, as allowed by thevalve 91, is developed in the conduit 00 the fluid coupling will becompletely full of oil and thus will be rotating the runner with minimumslip.

Since the applicant has provided a fluid flow control which regulatesthe quantity of fluid admitted into the working chamber of the fluidcoupling in minute quantities and has provided a working chamber whereinthe minute quantities of oil added to the chamber affect a body of oilgreater than is used for direct power transmission between the impellerH and the runner i9, it can be appreciated that the sensitivity of thefluid coupling to changes in speed caused by changing the volume of oilin the coupling is reduced. It will also be appreciated that a largerquantity of oil must be added to the coupling of this invention than toa conventional coupling to obtain a desired increase in volume of oil inthe working chamber of the coupling to obtain a desired speed changebetween the runner and the impeller. The greater quantity of oil flowingthrough the fluid coupling permits more rapid cooling of the coupling,and prevents overheating of the oil therein when the coupling is runningat speeds requiring relatively high slip between the impeller and therunner.

Figur 6 discloses a slightly modifled form of control for regulating thequantity of oil conducted to the work chamber of the fluid coupling. Inthis modification the elements of the apparatus are identical with theelements disclosed in Figure 5 and like elements bear like numerals. Inthis modification, however, the control valve l00a is placed in theconduit 90, the barometric control l02a controlling the valve I000 inthe same manner as described with regard the valve I00. When the valveMM is placed in position, as disclosed in Figure 6, the control thenfunctions as a volume control rather than as a pressure control asheretofore described with regard Figure 5. The valve "0:; throttles thequantity of oil passing through the conduit 96 all excess oil beingby-passed to the conduit 9% through the pressure relief valve 91. Whenusing the valve IBM in the conduit 06 to directly control the volume offluid passing through the conduit 86, the ports 06 should not berestrictions, or callbrated orifices, but are merely port passagesthrough which the controlled volume of fluid passes to the work chamber40 of the fluid coupling. The effect of the varied fluid volumesadmitted to the work chamber 45 are identically the same as previouslydescribed.

In Figure 7 there is disclosed a further modification wherein thepressure control of the flow of fluid to the work chamber of a hydrauliccoupling is used in combination with a conventional fluid coupling. Inthis arrangement the cylindrical chamber 31 is dispensed with and the antire'working chamber consists of the chamber 45a. 'I'he passageways 06in this instance are calibrated orifices and the degree of regulationobtained bymeans of these orifices over the volume of fluid admitted tothe work chamber 44 is regulated in the same manner as disclosed withregard Figure 5.

While the forms of the apparatus disclosed in this applicationconstitute preferred forms, yet it is within the scope of this inventionthat various constructional details can be modified without departingfrom the spirit of invention, and it is to be understood that while theinvention has been applied with speciflc'reference to' an aircraft yetthe invention is not so limited since 11; is readily applicable to anydevice which is to be driven through a fluid coupling and which requiresrelatively close regulation of the speed of the driven device.

Having thu fully described my invention, what I claim as new and desireto secure by Letters Patent is:

l. A variable filling fluid coupling comprising an impeller adapted tobe rotated, a runner in operative association with said impeller to bedriven thereby and forming therewith an active fluid circulation chamberfor power transmission, a fluid chamber associated with said runner andhaving a volume at least equal to the volume of the active fluid chamberbetween said runner and said impeller, a plurality of openings in saidrunner for providing continuous intercommunication between said fluidchamber and said chamber between. said runner and said impeller forinterflow of fluid therebetween whenever the quantity of fluid withinthe coupling is altered, means for continuously discharging a smallportion of the fluid from said. chamber, and means for continuouslyadding fluid to said coupling, the total change in volume of fluid insaid coupling eilfecting a speed change between said impeller and saidrunner which depends upon the change in volume of fluid in the activechamber.

2. A variable filling fluid coupling comprising 6 an impeller and acooperatingrunner forming a power transmission chamber for activecirculation of fluid therein, a. housing connected tosaid impeller andenclosing said runner having a space not occupied by the runner at leastequal to the volume or the power transmission chamber to form aninactive work fluid chamber, a plurality of openings in said runnerproviding continuous intercommunication between said active fluidchamber and said inactive fluid chamber for interflow of fluidtherebetween through the wall of said runner whenever the quantity offluid within the coupling is altered, means for continuously discharginga small portion of the fluid from said coupling, means for continuouslyadding fluid to said coupling, and automatically operated fluid pressurecontrol means associated with said last mentioned means to change thepressure of the fluid applied to said last mentioned means to therebyregulate the fluid flow therethrough.

3. A variable fllling fluid coupling comprising an impeller and acooperating runner forming a power transmission chamber for activecirculation of fluid therein, a housing connected to said impellerenclosing said runner having a space not occupied by the runner at leastequal to the volume of the power transmission chamber to form aninactive work fluid chamber, a plurality of openings in said runnerproviding continuous intercommunication between said active fluidchamber and said inactive fluid chamber for interflow of fluidtherebetween through the wall or said runner whenever the quantity offluid within the coupling is altered, fixed oriflce means forcontinuously discharging a small portion of the fluid from saidcoupling, flxed orifice means through which fluid is added to saidcouplin and fluid pressure control means associated with said lastmentioned means to regulate the pressure of the fluid applied at theinlet of said last mentioned oriflce means to change the fluid flowtherethrough and efl'ect a change in volume of the fluid in saidcoupling to produce a speed change between said impeller and said runnerwhich depends upon the change in volume of fluid in the activecompartment.

4. A variable filling fluid coupling comprising an impeller and acooperating runner iorming a power transmission chamber for activecirculation of fluid therein, a hmlslng connected to said impellerenclosing said mnner having a space not occupied by the runner at leastequal to the volume of the power transmission chamber to form aninactive work fluid chamber. a plurality of openings in said runnerproviding continuous intercomrnunication between said active fluidchamber and said inactive fluid chamber for interflow of fluidtherebetween through the wall 01 said runner whenever the quantity offluid within the coupling is altered. pressure differential fluid flowcontrol means for varying the volume of work fluid supplied to saidcoupling, pressure differential fluid flow control means for regulatingthe discharge of fluid from said coupling, and. means for changing thepressure of the fluid applied upon the inlet of the first mentionedcontrol means to change the volume flow of the fluid therethrough toeffect a speed change n said coupling.

5. A variable filling fluid coupling comprisin an impeller adapted to berotated. a runner in operative association with. sa d impeller to bedriven thereby, a fluid chamber assoc ated with saidrunner and having avolume at least eq to the volume or the active fluid chamber betweensaid runner and said impeller. passage means for roviding continuousinter-communication between said fluid chamber and said chamber betweensaid runner and said impeller for interflow oi fluid therebetweenwhenever the quantity of fluid within the coupling is altered; fixedoriflce means for regulating the quantity or fluid discharged from saidfluid coupling, a second flxed oriflce means for regulating the quantityor fluid admitted to said fluid coupling for varying the volume of fluidtherein, the variation in the speed differential between the runner andimpeller depending upon the change in the fluid volume placed in activecirculation, and; means for resulating the pressure of the work fluidapplied to said second mentioned orifice for regulating the flowtherethrough in accordance with the pressure drop across said orifice.

6. A variable fllling fluid coupling comprising an impeller adapted tobe rotated, a runner in operative association with said impeller to bedriven thereby, a fluid chamber associated with said runner and having avolume at least equal to the volume of the active fluid chamber betweensaid runner and said impeller, a plurality of openings in said runnerfor providing continuous intercommunication between said fluid chamberand said chamber between said runner and said impeller for inter-flow offluid therebetween whenever the quantity of fluid within the coupling isaltered, flxed orifice means for regulating the quantity of fluiddischarged from said fluid chamber, a second fixed oriflce means forregulating the quantity of. fluid admitted to said fluid coupling forvarying the volume of fluid therein,

whereby the variation in the speed differential between the runner andimpeller depends upon the change in the fluid volume placed in activecirculation, means for regulating the pressure of the work fluid appliedto said second mentioned 'oriflce for regulating the flow therethroughin accordance with the pressure drop across said oriflce, said lastmentioned means comprising a fluid pump for producing said pressure, andmeans for r regulating said pressure between predetermined maximum andminimum pressures.

7. A variable filling fluid coupling comprising an impeller adapted tobe rotated, a runner in operative association with said impeller to bedriven thereby, a fluid chamber associated with said runner and having avolume at least equal to the volume of the active fluid chamber betweensaid runner and said impeller, a plurality of openings in said runnerfor providing continuous intercommunication between said fluid chamberand said chamber between said runner and said impeller for interflow o1fluid therebetween when ever the quantity of fluid within the couplingis altered, flxed orlflce means for regulating the quantity of fluiddischarged from said fluid chamber, a second flxed orifice means forregulating the quantity of fluid admitted to said fluid coupling forvarying the volume of fluid therein, whereby the variation in the speeddifferential between the runner and impeller depends upon the change inthe fluid volume in active circulation, means for regulating thepressure of the work fluid applied to said second. mentioned oriflce forregulating the flow therethrough in accordance with the pressure dropacross said 011- dice. said last mentioned means comprising means fordelivering fluid to said second mentioned oriflee and for placing thefluid so delivered under pressure, means for changing the value orpressure of the fluid so delivered to said second mentioned orifice tothereby change the pressure drop across the orifice and thus change thevolume flow therethrough for controlling speed changes of said and saidchamber between said runner and said impeller for interflow oi! fluidtherebetween whenever the quantity of fluid within the coupling isaltered. fixed orifice means for regulating the quantity of fluiddischarged from said fluid chamber, a second fixed orifice means forregulating the quantity of fluid admitted to said fluid coupling forvarying the volume of fluid therein. whereby the variation in the speeddiiierential between the runner and impeller depends upon 7 the changein the fluid volume in active circulation, means for regulating thepressure of the work fluid applied to said second mentioned oriflce forregulating the flow therethrough in accordance with the pressure dropacross said oriflee, said last mentioned means comprising means fordelivering fluid to said second mentioned orifice and for placing thefluid so delivered under pressure. means for changing the value oipressure oi the fluid so delivered to said second mentinned orifice tothereby change the pressure drop across the orifice and thus change thevolume flow therethrough for controlling speed changes 01' saidcoupling, means for by-passing said last mentioned means for preventingpressure increase above a predetermined maximum irrespective of speedcontrol, and means in series circuit flow relation with said aforesaidlast mentioned means for preventing said pressure from falling below apredetermined minimum to establish a minimum fluid flow therethrough forlubrication purposes.

9. A variable filling fluid coupling comprising an impeller adapted tobe rotated, a runner in operative association with said impeller to bedriven thereby and forming therewith an active fluid circulation chamberfor power transmission. a housing connected to said impeller enclosingsaid runner having a space not occupied by the runner at least equal tothe volume of the active fluid chamber between said runner and saidimpeller. a. plurality oi openings in said runner for providingcontinuous intercommunication between said space and said chamberbetween said runner and said impeller for interflow oi. fluidtherebetween whenever the quantity of fluid within the coupling isaltered, means for continuously discharging a small portion of the fluidfrom said chamber, and means for continuously adding fluid to saidchamber, the total change in volume of fluid in said coupling eiiectinga speed change between said impeller and said runner which depends uponthe change in volume of fluid in the active chamber.

MER'I'ON H. BLANK.

